With development of communications services, a positioning service is important in reality as an indispensable part of mobile communications and personal communications services. The positioning service is a value-added service for obtaining location information (such as longitude and latitude coordinate information) of a mobile terminal through a network of a mobile telecommunications operator, and providing a corresponding service for a user with support of an electronic map platform.
A time difference of arrival (TDOA) technology is a currently common positioning technology. According to a principle of the technology, when one mobile terminal is positioned, three or more network nodes (such as base stations) may be used as reference nodes. Location information of each reference node is known. When the mobile terminal sends an uplink sounding reference signal (SRS) to each reference node, a location of the mobile terminal is determined according to TDOAs of the SRS on different reference nodes. Alternatively, when each reference node sends a downlink positioning reference signal (PSR) to the mobile terminal to probe a signal, a location of the mobile terminal is determined according to a TDOA of the PSR on the mobile terminal. A method for implementing positioning according to a TDOA of an uplink signal is also referred to as an uplink-time difference of arrival (UTDOA) positioning method. A method for implementing positioning according to a TDOA of a downlink signal is also referred to as an observed time difference of arrival (OTDOA) positioning method.
However, precision of location information obtained according to a TDOA of a signal is inversely proportional to bandwidth of the signal. For example, a pulse width of an ultra-wideband system signal is at a nanosecond level, and bandwidth of the signal can reach thousands of megahertz (GHz). Therefore, an error between the obtained location information and actual location information is at a centimeter level. However, bandwidth of a PSR and an SRS that are used for positioning in a current communications system is 20 megahertz (MHz), and the bandwidth is limited. Consequently, an error of location information obtained by means of positioning is relatively large, and precision is relatively low.
Conventionally, a signal may be sent by using a carrier aggregation technology, to increase bandwidth of the signal. However, an aggregated reference signal generated after carrier aggregation is performed on multiple signals has a great change in waveform when compared with the signals before the aggregation. Therefore, a signal receiving device cannot accurately determine whether a received signal is the aggregated reference signal. An error is relatively large when a transmission time of the aggregated reference signal is determined. Consequently, positioning fails due to a relatively large error of location information obtained by means of positioning.